Hi! I'm a relatively new Betta fish owner, I got mine in September. His name is Dobis and he is a very beautiful light blue crown Betta. I recently moved him into a larger bowl (1.5 gal, he used to be in a 1 gal). Also I got him a water heater, I figured he needed it because-- being a tropical fish-- he is not equipped for Vermont weather!

Recently I've noticed his (very light blue) head turns splotchy black and his eyes turn very dark. And his gils (not sure if that's what they actually are, just a guess) turn black and fan out around his face. I'm really worried about him! Does anyone know what it is? Or how I can help him? Thank you so much :)

WOW is all I can say. He is gorgeous. Has his behavior changed at all?
My best guess is that the new space and heater sparked him to marble. He looks perfectly fine to me. Marbling bettas change color their whole lives xD I'm quite jealous, to be frank.
The "fanning" cheeks are probably him flaring because he's happy.

In something that small make sure you are doing 2 water changes a week - one 50% and one 100% including a thorough rinsing of the gravel and any dechor. Redose conditioner with water changes, of course.

Here's how you can do large changes without shocking:

Quote:

To do a water change, use a little cup like a plastic solo cup - this cup must be only for him and have never been used with soap or other chems. Scoop him up in this cup (keep him in the cup about 1/4 full of water - it doesn't need to be much because he won't be in it for long) and leave him in the cup while you change his water. To do the 50% use a turkey baster - dedicated only to him that has never seen soap or chems - and drag it through the gravel and try to suck as much of the poop out as possible, in addition to 50% of the water. Use a thermometer under the running tap to get it to be the same temp as the water that is normally in his tank. When the thermometer says the flowing tap is the right temp, fill back up his tank. At this point, add the conditioner (dose for how much water you change - if you change half the water you add half gallon worth of conditioner, If you do a 100% water change dose for the full gallon change). Float his plastic cup with him in it in the new water. Slowly add a couple tablespoons of the new water into his cup every 10 minutes for at least an hour. Finally, dump him in gently but try to get as little of the old cup water back into the tank as possible. When you do the weekly 100% you will do mostly the same thing except empty his tank fully and rinse everything in it very well under warm water but never use soaps or chemicals. Once it's fully cleaned/rinsed you can refill it and repeat the cup/acclimate phase.